Add if-defined conditional

This fixes gstein#18

ezt.py

@@ -286,11 +286,11 @@ def _parse(self, reader, for_names=None, file_args=(), base_printer=None):
             program.append((cmd,
                             (_prepare_ref(args[1], for_names, file_args),
                              reader, printers[-1]), filename, line_number))
-        elif cmd == 'if-any':
+        elif cmd == 'if-any' or cmd == 'if-defined':
           f_args = [ ]
           for arg in args[1:]:
             f_args.append(_prepare_ref(arg, for_names, file_args))
-          stack.append(['if-any', len(program), f_args, None, line_number])
+          stack.append([cmd, len(program), f_args, None, line_number])
         else:
           # implied PRINT command
           if len(args) > 1:
@@ -390,6 +390,18 @@ def _cmd_if_any(self, args, fp, ctx, filename, line_number):
         break
     self._do_if(value, t_section, f_section, fp, ctx)
 
+  def _cmd_if_defined(self, args, fp, ctx, filename, line_number):
+    "If all values are defined, then T else F."
+    (valrefs, t_section, f_section) = args
+    value = 0
+    try:
+      for valref in valrefs:
+        if _get_value(valref, ctx, filename, line_number):
+          value = 1
+    except UnknownReference as e:
+      value = 0
+    self._do_if(value, t_section, f_section, fp, ctx)
+
   def _cmd_if_index(self, args, fp, ctx, _filename, _line_number):
     ((valref, value), t_section, f_section) = args
     items, idx = ctx.for_index[valref[0]]
@@ -505,6 +517,7 @@ def _get_value(refname_start_rest, ctx, filename, line_number):
   for blocks take precedence over data dictionary members with the
   same name.
   """
+  # print('\nrsr',refname_start_rest,'\n',file=sys.stderr)
   (refname, start, rest) = refname_start_rest
   if rest is None:
     # it was a string constant

tests/ezt_test.py

@@ -111,6 +111,18 @@ def testIsAny(self):
     d = self._runTemplate(t, {'O1': [], 'O2': None, 'O3': 0, 'O4': 'hi'})
     self.assertEqual('\n!O1\n!O2\nO3\nO4\n!O1O2\nO1O4\n', d)
 
+  def testIfDefined(self):
+    t = """
+[if-defined O1]O1[else]!O1[end]
+[if-defined O2]O2[else]!O2[end]
+[if-defined O3]O3[else]!O3[end]
+[if-defined O4]O4[else]!O4[end]
+[if-defined O1 O2 O3 O4]O1O2O3O4[else]!O1O2O3O4[end]
+[if-defined O3 O4]O3O4[else]!O3O4[end]
+"""
+    d = self._runTemplate(t, {'O3': 0, 'O4': 'hi'})
+    self.assertEqual('\n!O1\n!O2\nO3\nO4\n!O1O2O3O4\nO3O4\n', d)
+
   def testIfIndex(self):
     o = [1, 4, 9, 16, 25]
     t = """